Notes on Genus: Megrivirus


Type member: Melegrivirus A


General Description

The genus Megrivirus is one of the genera in the family Picornaviridae and is named from the host of the type species (turkey, genus name Meleagris). Genome organisation is fairly conserved within the family but members of this genus have no leader protease, a single 2A protein and one or more proteins of unknown function in the region immediately downstream of the capsid proteins.


Virions isometric (icosahedral), not enveloped 30 nm in diameter, made of 60 units (protomers) each consisting of one molecule of each of three surface coat proteins and with a fourth internal capsid protein.


Monopartite positive sense single-stranded RNA 9.1 kb in length. There is a genome-linked protein (VPg) at the 5'-terminus and a 3'-polyA tail.

Genus Genomic Organization

The RNA encodes a single polyprotein that is subsequently processed into the functional products. The major structural proteins are encoded at the N-terminus.

Type Member Genomic Organization

The genome of about 9,100 nucleotides is translated into a single polyprotein, which is subsequently processed into at least twelve products:
1A+1B   41.6 kDa Coat protein VP4+VP2 precursor
1C 17.9 kDaCoat protein VP3 (surface capsid protein)
1D 26.3 kDaCoat protein VP1 (surface capsid protein)
X 46.9 kDa Unknown protein(s)
2A 22.6 kDanon-structural protein
2B 20.3 kDanon-structural protein
2C 41.8 kDanon-structural protein
3A 17.1 kDanon-structural protein
3B 3.1 kDa Genome-linked protein (VPg)
3C 22.6 kDaprotease
3D 54.1 kDapolymerase